Light-sensitive diazotype material and diazo compounds



United States Patent 3 290 150 LIGHT-SENSITIVE Dll tZtlTYPE MATERIAL AND DIAZO COMPGUNDS Jan Eenshuistra, Bernardus Hubertus Huibers, and Leo Hubertus Joseph Van Helden, all of Venlo, Netherlands,

assignors to Chemische Fabriek L. van der Griten N.V.,

Venlo, Netherlands, a corporation of the Netherlands No Drawing. Filed Feb. 19, 1963, Ser. No. 259,731

Claims priority, applicatitgr; 131 segherlands, Nov. 10, 1958, 18 Claims. (:1. 96-49) This application is a continuation-in-part of application Serial Number 851,967, now abandoned, filed November 10, 1959.

The invention relates to diazotype material of the socalled one-component type and of the so-called two-component type, which contains a p-amino benzene diazocompound, derived from an ortho-amino-phenyl alkyl ether, in which both the hydrogen atoms of the amino group have been replaced by hydrocarbon radicals.

Belgian Patent No. 564,343 describes a process in which diazotype material is used which contains a diazo compound of the general formula:

0R in which X represents an anion, R represents an alkyl group with at most 4 carbon atoms, R represents an alkyl group with at most 4 carbon atoms or an aralkyl group with at most 7 carbon atoms, and R represents an alkyl group with at most 4 carbon atoms.

Diazo compounds of this type are very sensitive to the light of the mercury vapour lamps commonly used in the diazotype process, both of high-pressure lamps and of low-pressure lamps, and both of the actinically fluorescent and of the non-fluorescent lamps.

Diazotype material sensitized with such a diazo compound is extremely suitable for the visual observation of the end point of the exposure in the process of copying in the light of actinically fluorescent mercury-vapour lamps.

The diazo compounds of this type having small alkyl groups, e.g., 1-diazo-4-dimethylamino-3-methoxybenzene and 1 diazo 4 dimethylamino 3 ethoxybenzene, yield light azo-dyestuifs and their coupling activity is low. In practice the compounds in which the amino group carries larger alkyl groups or an aralkyl group are therefore preferred. They yield darker azo-dyes-tufis and they couple more actively, which is especially important for diazotype material for so-called semi-wet development.

In the production of sensitizing liquids for many diazotype materials, e.g., diazotype paper, water is preferably used as solvent. Aqueous solutions of diazo compounds in which the amino group carries larger alkyl groups, such as n-butyl, n-amyl, and n-hexyl groups, often exhibit an inconvenient capillary action. During the sensitization of the usual base-papers they penetrate far into the paper. The visual observation of the endpoint of the exposure is impeded by this and both the light-sensitivity of the diazotype material and the strength of the copies decrease.

As is known, diazotype copies show often discolouration upon continued exposure to light. Copies on diazotype material of the kind used in the process of Belgian Patent No. 564,343, which has been sensitized with a diazo compound in which the amino group carries an aralkyl group, often show considerable discolouration. The aqueous solutions of the latter diazo compounds moreover show a greater capillary action than those of corresponding diazo compounds in which the amino group carries small alkyl groups, though not as large as those of the corresponding compounds with larger alkyl groups.

Besides the diazo compounds mentioned in the said Belgian patent, corresponding compounds having a chlorine atom, a methyl group or an ethoxy group in the para-position with respect to the alkoxy group are known. These diazo compounds, and the aqueous solutions and diazotype materials manufactured with them, possess the same disadvantages as described above with respect to the diazo compounds mentioned in the said Belgian patent and to the aqueous solutions and diazotype materials manufactured with those diazo compounds.

The diazotype material according to the present invention contains a p-amino-benzene diazo compound, derived from an ortho-aminoaphenyl alkyl ether, in which one of the hydrogen atoms of the amino group has been replaced by -a substituted or a non-substituted cyclohexyl group, and the other hydrogen atom by a substituted or a non-substituted alkyl group with at most 3 carbon atoms. Besides the diazo group, the amino group and the alkoxy group, the benzene nucleus may carry yet another substituent, such as a halogen atom, a methyl group or an alkoxy group, containing at most 4 carbon atoms, in the para-position with respect to the alkoxy group.

Diazo compounds of structure just set forth are new chemical compounds per se. With suitable azo-dyestuif components they yield dark azo-dyest-uifs, and their aqueous solutions exhibit a much lower degree of the objectionable capillary action, or none at all, compared with the aqueous solutions of corresponding diazo compounds having an acyclic larger alkyl group or an aralkyl group on the amino group instead of the specified cyclohexyl group. Copies on diazotype material according to the present invention also show less discolouration upon exposure to light than copies on corresponding diazotype material sensitized with corresponding diazo compounds having an aralkyl group instead of the specified cyclohexyl group.

The diazotype material according to the present invention moreover possesses the valuable properties of very high light sensitivity and of suitability for visual observation of the end point of the exposure when the copying is effected by use of an actinic-ally fluorescent mercury vapor lamp such, for example, as a lamp of the Philips TL 5 type. In these respects and others they have good properties of the kinds possessed by the diazotype material used in the process of Belgian Patent No. 564,343.

These properties are not found with diazotype material sensitized by means of a 4-cyclohexylamino 3-methoxybenzene diazonium salt or by means of a 4-N-ethyl-N- cyclohexyl aminobenzene diazonium salt, which diazo compounds have been proposed heretofore (see US. Pa-t ent 2,618,555) for use in a two-component diazotype material containing a reducible metal salt, such as silver nitrate to be used in a negative reproduction process.

If diazotype materials sensitized by means of those diazocompounds, but being free from the reducible metal salt, are compared with the diazotype materials according to the present invention it is found that their lightsensitivity is about half or less than half that of the diazotype material according to the invention and for this reason alone they are not comparable with those used according to the invention. Moreover upon making copies using a printer equipped with actinically fluorescent mercury-vapour lamps of the type Philips TL 5 (see Example 1 of Belgian Patent No. 564,343) visual observation of the endpoint of the exposure results in copies with a heavily fogged underexposed background when diazotype materials sensitized by means of the above mentioned diazocompounds are used.

The excessive penetration of the sensitizing liquid into the support of the material during the manufacture of diazotype material is not only dependent on the diazocom- J9 pound used, but also on other substance present in the liquid, especially on the solvent used, as well as on the temperature of the liquid (the higher the temperature, the greater the capillary action; in practice sensitizing liquids of about room temperature are preferably used). It is further dependent on the sensitizing method employed, in which connection for example the time which elapses between the application of the sensitizing liquid and the drying may be very important, and also on the nature of the support. If the support consists, for example, of superficially hydrolysed cellulose acetate film, in most cases there is no risk of aqueous sensitizing liquids penetrating too far, since as a rule they can only impregnate the hydrolysed layer at the surface of the film. This even holds good for many sensitizing liquids made up with a mixture of water and a comparatively large quantity of alcohol. If, however, the support consists of a poorly sized paper, even sensitizing liquids With a very small capillary action may penetrate too far.

In the manufacture of diazotype material according to the present invention the above factors have to be taken into account. In assessing the light-discolouration of copies on diazotype material according to the present invention allowance has also to be made for the influences exerted on the discolouration by substances present in the copies besides the light-decomposition products of the diazo compounds, as well as by the nature of the support.

Besides those used according to the examples which follow, the following diazo compounds may especially be mentioned as examples of diazo compounds which are suitable for the manufacture of diazotype material according to the present invention:

4-N-hydroxyethyl-N-cyclohexyl amino 3 n propoxybenzene diazonium chloride, zinc chloride double salt, 4-N-n-propyl-N-(4'-metl1yl cyclohexyl) amino-3- methoxy 6-chlorobenzene diazonium chloride, zinc chloride double salt,

4-N-methyl-N-cyclohexyl amino 3 ethoxy 6 methylbenzene diazonium chloride, cadmium chloride double salt,

4-N-methyl N-cyclohexyl amino-3-n-butoxy-6-brornobenzene diazonium borofluoride,

4-N-methyl N-cyclohexyl amino-3-ethoxy-6-ethoxy benzene diazonium-p-chlorobenzene sulphonate.

4-N-methyl-N-cyclohexylamino-3-methoxy-6-methoxybenzene diazonium-p-chlorobenzene sulphonate 4-N-methyl-N-cyclohexylamino-3-n-propoxy-6n-propoxy benzene diazonium chloride, zinc chloride double salt,

4-N-methyl-N-cyclohexylamino-3-n-butoxy-6-n butoxy benzene diazonium sulphate.

The diazotype material according to the present invention may of course also contain mixtures of diazo compounds.

The diazo compounds used in the diazotype material according to the invention may be prepared in several ways. The starting material may be, for example, o-nitro phenol, which is alkylated and reduced. The o-alkoxy aniline obtained is alkylated in two steps, :at first with cyclohexyl bromide or with cyclohexanone and methyl formate in an autoclave, and afterwards with another 'alkylating agent, e.g., dimethyl sulphate. The o-alkoxy N-cyclohexyl N-alkylaniline obtained is then provided with a nitroso group in the para-position with respect to the amino group by treatment with nitrous acid, or it is nitrated or coupled to diazotized 2,5-dichloro-aniline. The nitroso or nitro compound or the azodyestuff thus obtained is reduced to an amino compound and this is converted into a diazonium compound by treatment with nitrous acid. The diazonium compound can be obtained as a double salt, for example by precipitation with zinc chloride or sodium borofluoride.

For the preparation of diazo compounds having a chlorine atom, a methyl group or an alkoxy group in the para-position with respect to the alkoxy group to starting material is p-chloro, p-methyl or p-alkoxy o-nitrophenol. With respect to the cyclohexylation and alkylation referred to above, it is to be noted that hydrogen atoms of the cyclohexyl and/or of the .alkyl groups may be replaced by substituents such as hydroxy and methyl groups or chlorine atoms.

The following examples will serve to illustrate the invention:

Example 1 White base-paper of Weight g./m. as used for the diazotype process is sensitized as follows. One side of the paper is brought int-o contact with the surface of the following sensitizing liquid (temperature 18 to 20 C.), which is contained in a trough:

20.5 g of 4-N-n-propyl-N-cyclohexylamino-3-rnethoxybenzene diazonium chloride, zinc chloride double salt,

5 g. of tartaric acid,

20 cm. of polyvinyl acetate dispersion, Vinnapas H.60, I

in 10-00 cm. of water.

Immediately afterwards the wet paper is fed over a glass doctor blade, in consequence of which only a thin layer of 8 to 9 g./m. of the sensitizing liquid remains on the paper surface. Within about 15 seconds after passing the doctor blade the paper is dried to a humidity of 34% The sensitized surface contains approximately 0.45 millimole of diazo compound per m.

The light-sensitive side of a sheet of the diazotype paper thus prepared is covered with a sheet of tracing paper on which a pencil drawing has been made, and exposed in an exposure apparatus equipped with actinically fluorescent low-pressure mercury-vapor lamps. Exposure is continued until in the proportions which are in contact with the blank parts of the drawing all of the diazo compound bleached out. The moment at which the exposure has to be terminated can be determined very well by visual observation (e.g., from the direction of the lightsource) of the change of colour which occurs in the lightsensitive layer during the exposure. This moment is soon reached.

The latent diazotype copy thus obtained is developed by applying on its image surface a layer of approximately 8 g./m. of a developing liquid of the following composition:

31 g. of thiourea,

6.5 g. of phloroglucinol,

6.5 g. of resorcinol,

2 g. of isopropylnaphthalene sulphonic acid sodium salt, 5 g. of sorbitol,

15 g. of saccharose,

53 g. of potassium tetraborate (5 aq.),

9 g. of potassium hydroxide,

in 1000 cm. of water.

The developed copy shows a strong dark-brown image on a clear white background.

When, instead of the above-mentioned diazo compound, the corresponding di-n-butylamino compound is used, the sensitizing liquid penetrates too far into the paper. In that case the determination of the endpoint of the exposure is less easy, and the diazotype copy shows a less strong dark-brown image.

When, instead of the abovementioned diazo compound, the corresponding N-propyl N-benzylamino compound is used, a diazotype copy with a dark-brown image is obtained, which upon exposure to light shows considerably greater discolouration than the diazotype copy according to the example.

The diazo compound used according to this example is prepared as follows:

By reaction of o-anisidine with cyclohexyl bromide, omethoxy N-cyclohexylaniline is prepared. This compound is propylated with propyl bromide to o-methoxy- N cyclohexyl-N-n-propyl aniline (boiling point 15 C.). This product is nitrated, and the p-nitro-omethoxy-N-cyclohexyl-N-n-propylaniline thus obtained is reduced and converted into the diazo compound in the usual way.

Example II White base-paper of weight 30 g./m. as used for the diazotype process is sensitized in the manner described in Example I with a solution (temperature 18 to 20 C.) of:

19.25 g. of 4-N-methyl-N-cyclohexylamino-3-rnethoxy 6- chlorobenzene diazonium chloride, zinc chloride double salt,

g. of tartaric acid,

g. of naphthalene-1,3,6-trisulphonic acid as sodium salt,

0.8 g. of methyl cellulose,

In 1000 cm. of water,

and dried.

The sensitized surface contains approximately 0.45 millimole of diazo compound per m. The diazotype paper possesses good keeping qualities.

A sheet of the diazotype paper thus prepared is image wise exposed as described in Example I. The moment at which the exposure has to be terminated can be observed very well and is soon reached.

. The latent diazotype copy thus obtained is developed by treating it with a developing liquid of the following composition: p

15 g. of thiourea,

4 g. of phloroglucinol, I g

1.2 g. of Z-ethylhexyl sulphuric acid mono-ester 'as so-' dium salt (commercially available under the name of Tergitol 08),

2.5 g. of benzoic acid,

15 g. of sodium 'benzoate,

150 g. of sodium formate,

in 1000 cm. of water and by heating-and drying it subsequently over an electric heater. The developed copy shows a strong black image on a clear-white background.

When, instead of the abovementioned diazo compound, the corresponding N-methyl-N-n-hexyl-amino compound is used, the sensitizing liquid penetrates too far into the paper. In that case the determination of the endpoint of the exposure is less easy, and the diazotype copy shows a less strong black image.

When, instead of the abovementioned diazo compound, the corresponding N-methyl-N-benzylamino compound is used, a diazotype copy with a black image is obtained, which upon exposure to light shows a considerably greater discolouration than the diazotype copy according to the example.

The diazo compound used according to this example is prepared as follows:

By reaction of S-chloro-Z-methoxyaniline (commercially available as Echtrot R.C. base) with cyclohexanone and methyl formate in an autoclave at 225 C. and 38 at. during 3 hours, 5-chloro-2-methoxy-N-cyclohexylaniline (boiling point mm, 175-190 C.) is prepared. This compound is methylated with dimethyl sulphate to 5- chloro 2 methoxy N cyclohexyl N methylaniline (boiling point mm l40l60 C.). This product is nitrated. The 5 chloro 4 nitro --2 methoxy N cyclohexyl-N-methylaniline thus obtained is reduced and converted into the diazo compound in the usual way.

Example 111 White base-paper of weight 80 g./m. as used for the diazotype process is pre-coated with approximately 10 g./m. of the following liquid:

100 cm. of colloidal silica dispersion Satessa 14,

2 g. of polyvinyl alcohol, Rhodoviol BS 10, in 900 cm? of water,

and dried.

The surface thus treated is sensitized in the manner described in Example I with a solution (temperature 18 to 20 C.) of

24 g. of 4-N-methyl-N-cyclohexylamino-3-ethoxybenzene diazonium chloride, zinc chloride double salt,

g. of tartaric acid,

10 g. of 2,3-dihydroxy-naphthalene,

42.5 g. of caffeine,

20 cm. of polyvinyl acetate dispersion, Vinnapas H. 60,

in 1000 cm. of water,

and dried.

The sensitized surface contains approximately 0.65 millimole of diazo compound per m.

A sheet of the diazotype paper thus prepared is imagewise exposed as described in Example I. The moment at which the exposure has to be terminated can be observed very well and is soon reached.

The latent diazotype copy thus obtained is developed by exposing it for some tens of seconds to hot concentrated moist ammonia vapour.

The developed copy shows a strong dark-blue image on a clear white background.

When, instead of the abovementioned diazo compound, the corresponding di-n-propylamino compound is used, the sensitizing liquid penetrates too far into the paper. In that case the determination of the endpoint of the exposure is less easy, and the diazotype copy shows a less strong dark-blue image.

When, instead of the abovementioned diazo compound, the corresponding N-methyl-N-benzylamino compound is used, a diazotype copy with a dark-blue image is obtained, which upon exposure to light shows considerably greater discolouration than the diazotype copy according to the example.

The diazo compound used according to this example is prepared as follows:

By reaction of o-phenetidine with cyclohexyl bromide, Z-ethoxy-N-cyclohexylaniline (boiling point mm C.) is prepared. This compound is methylated to 2- ethoxy-N-cyclohexyl-N-Inethylaniline (boiling point mm, 164 C.). This product is nitrated, and the 4-nitro-2- ethoxy-N-cyclohexyl-N-methylaniline thus obtained is reduced and converted into the diazo compound in the usual way.

When instead of 24 g. of 4-Namethyl-N-cyclohexylamino-3-et'hoxy benzene diazonium chloride, zinc chloride double salt, 28 g. of 4-N-ethyl-N-cyclohexylamino-3- ethoXy-6-ethoxybenzene diazonium chloride, zinc chloride double salt are used, a diazotype paper according to the invention, with good qualities is obtained. A copy made on this paper shows a strong blue image.

The lastmen-tioned diazo compound can be prepared as follows: aminohydroquinone diethylether is ethylated to N ethyl amino hydroquinone diethylether. This compound is reacted with cyclohexanon and methyl forrnate in an autoclave at 250 C. The reaction product, N ethyl N cyclohexylaminohydroquinone diethylether is a tan coloured oil boiling at -200" C. at 15 mm. Hg pressure.

The oil is nit-rated and the resulting 4-N-ethyl-N-cyclohexylamino-3,6-diethoxy-nitrobenzene is reduced to the corresponding amino compound, which is converted into the diazocompound in the usual way.

What we claim is:

1. A diazotype material that gives a positive diazo-type copy of a positive original comprising -a support sensitized with a light-sensitive composition comprising a compound having the structure in which:

R is an alkyl group containing at most 3 carbon atoms,

R comprises a cyclohexyl radical,

R is an alkyl group containing at most 4 carbon atoms,

X is an anion, and

Y is selected from the class consisting of hydrogen and halogen atoms, a methyl group and alkoxy groups containing at most 4 carbon atoms.

2. A diazotype material as defined in claim 1, in which R contains at most 2 carbon atoms.

3. A diazotype material as defined in claim 1, in which R contains at most 2 carbon atoms, X is a chlorine atom and Y is a hydrogen atom.

4. A diazotype material as defined in claim 1, in which R, contains at most 2 carbon atoms, X is a chlorine atom and Y is a chlorine atom.

5. A diazotype material that gives a positive diazo-type copy of a positive original comprising a support sensitized with a light-sensitive composition comprising a l-diazo 4- (methyl) (cyclohexyl) amino 3-methoxy benzene.

6. A diazotype material that gives a positive diazo-type copy of a positive original comprising a support sensitized With a light-sensitive composition comprising a 1-diazo 4- (methyl) (cyclohexyDamino 3-rnethoxy 6-ohloro benzene.

7. A diazotype material that gives a positive diazo-type copy of a positive original comprising a support sensitized with a light-sensitive composition comprising a l-diazo 4- (methyl) (cyclohexyl) amino 3-ethoxy benzene.

8. A diazotype material that gives a positive diazo-type copy of a positive original comprising a support sensitized with a light-sensitive composition comprising a l-diazo 4-(methyl) (cyclohexyl) amino, 2,5-diethoxy benzene.

9. A positive process for the production of -a diazo? type print which comprises imagewise exposing to actinic light a diazotype material as defined in claim 1 and developing the exposed material by applying to it a film of a liquid developer containing phloroglucinol.

10. A positive process for the production of a diazotype print which comprises imagewise exposing to actinic light a diazotype material as defined in claim 1 containing an azo coupling component with the diazo compound, and developing the exposed material by treating it with moist ammonia gas.

8 11. A diazo compound having the structure Y I /R1 XNg- N\ R2 I s in which:

R is an alkyl group containing at most 3 carbon atoms,

R comprises a cy-clohexyl radical,

R is an alkyl group containing at most 4 carbon atoms,

X is an anion, and

Y is selected from the class consisting of hydrogen and halogen atoms, a methyl group and alkoxy groups containing at most 4 carbon atoms.

12. A diazo compound as defined in claim 11, in which R, contains at most 2 carbon atoms.

13. A diazo compound as defined in claim 11, in which R contains at most 2 carbon atoms and Y is a chlorine atom.

14. A diazo compound as defined in claim 11, in which R contains at most 2 carbon atoms, X is a chlorine atom, and Y is a hydrogen atom.

15. A diazo compound as defined in claim 11, in which R contains at most 2 carbon atoms, X is a chlorine atom and Y is a chlorine atom.

16. A compound comprising l-diazo 4-(methyl) (cyclohexyl) amino 3-met'hoxy 6-chloro'benzene.

17. A compound comprising l-diazo 4- (methyl) (cyclohexyl) amino 3-ethoxybenzene.

18. A compound comprising l-diazo 4- (methyl) (cyclohexyl) amino 2,5-diethoxy benzene.

References Cited by the Examiner UNITED STATES PATENTS 2,405,523 8/1946 Sease et al. 9691 X 2,542,715 2/1951 Slifkin 96-91 2,618,555 11/1952 Reichel 96-91 X 3,081,166 3/1963 Van Loon et a1. 9691 X NORMAN G. TORCHIN, Primary Examiner. R. L. STONE, C. BOWERS, Assistant Examiners. 

1. A DIAZOTYPE MATERIAL THAT GIVES A POSITIVE DIAZO-TYPE COPY OF A POSITIVE ORIGINAL COMPRISING A SUPPORT SENSITIZED WITH A LIGHT-SENSITIVE COMPOSITION COMPRISING A COMPOUND HAVING THE STRUCTURE
 9. A POSITIVE PROCESS FOR THE PRODUCTION OF A DIAZOTYPE PRINT WHICH COMPRISES IMAGEWISE EXPOSING TO ACTINIC LIGHT A DIAZOTYPE MATERIAL AS DEFINED IN CLAIM 1 AND DEVELOPING THE EXPOSED MATERIAL BY APPLYING TO IT A FILM OF A LIQUID DEVELOPER CONTAINING PHLOROGLUCINOL. 